Gauge recording maximum pressure

ABSTRACT

Device for visual indication of a maximum fluid pressure condition reached during a given interval of time. Useful for the in-flight recording of fluid pressure condition e.g., in the reduction gear box of a jet engine where excessive pressures are indicative of incipient failures, the device comprises a body having a cavity in fluid pressure communication with system fluid, an indicator movable relative to the body cavity in response to changes in system fluid pressure, and locking means limiting indicator travel to a single direction indicative of a relatively higher pressure condition in the system.

United States Patent 1191 Smith 1451 Dec. 18, 1973 GAUGE RECORDINGMAXIMUM PRESSURE [75] Inventor: Charles Harry Smith, Glendale,

Calif.

[73] Assignee: Purex Corporation, Ltd., Lakewood,

Calif.

[22] Filed: July 26, 1971 [2l] App]. No.: 166,016

8/1960 'Astl.... 73/396 X Primary Examiner-Richard C. Queisser AssistantExaminer-Daniel M. Yasich Att0rney-White, Haefliger & Bachand ABSTRACTDevice for visual indication of a maximum fluid pressure conditionreached during a given interval of time. Useful for the in-flightrecording of fluid pressure condition e.g., in the reduction gear box ofa jet engine where excessive pressures are indicative of incipientfailures, the device comprises a body having a cavity in fluid pressurecommunication with system fluid, an indicator movable relative to thebody cavity in response to changes in system fluid pressure, and lockingmeans limiting indicator travel to a single direction indicative of arelatively higher pressure condition in the system.

7 Claims, 4 Drawing Figures GAUGE RECORDING MAXIMUM PRESSURE BACKGROUNDOF THE INVENTION This invention has to do with pressure recordingdevices. The invention is more particularly concerned with devicesrecording visually the maximum pressure history of a fluid containingsystem. The present device was occasioned by the need for accurately andsimply monitoring jet engine pressure conditions, but it is applicableto other fluid pressure characterized environments.

In jet engines used in aircraft and in like turbine devices, variouspumps and generators are run off the main drive shaft by means of areduction gear train. The reduction gear drive may be located in anaccessory gear box just behind the compressor and just ahead of thecombustion chamber portion of the turbine. The box is sealed againstundue pressure development therein which may lead to bearing failure.Because the seal failure is a prelude to bearing failure and much lesscostly to repair, it is highly desirable to monitor pressure within theaccessory gearbox during flight. To successfully monitor this pressure,it is necessary to provide a monitoring device which is rugged inconstruction, accurate despite vibration and capable of ready visualpresentation of maximum fluid pressures encountered during flight. Inaddition, the device must stably record maximum pressures encounteredalthough the pressure maysubsequently drop, as when the engines shutdown after flight.

PRIOR ART Numerous devices have been made available for recording fluidpressure conditions over time, but none is known to us providing thefeatures of the present device. Devices specifically intended for jetengine accessory gear box use have lacked sufficient accuracy ordurability in the vibration prone environment in which they arenecessarily used.

SUMMARY OF THE INVENTION It is a major objective of the presentinvention to provide a reliable, low cost, long wearing and accuratevisual indicating device highly adapted to the monitoring of maximumpressure conditions over time or during a cycle.

In particular, the invention provides a device for indicating fluidpressure in a system experiencing varying conditions of pressure. Thedevice comprises a pressure resistant body defining a cavity, port meansthrough the body maintaining the body cavity in continuous fluidpressure communication with system fluid, an indicator movable relativeto the body cavity in response to changes in system fluid pressure, and

locking means limiting indicator travel to a single direction indicativeof a relatively higher pressure condition in the system. The indicatormay comprise a rod movable relative to the locking means. The lockingmeans may include an element adapted to engage the rod, mounted to passthe rod moving relatively thereto in one direction responsive torelatively increased fluid pressure in the system and to lock the rodagainst movement in the reverse direction. The fluid pressure indicatingdevice may further include piston means adapted to travel within thebody cavity in response to fluid pressure changes within the cavity, theindicator being carried by the piston to be movable therewith. A

flexible support may be provided for the piston in the cavity, defininga cavity wall and adapted to permit relative piston movement within thecavity.

In certain embodiments hereof, the device includes piston means movablysupported within the cavity, e.g., by a diaphragm fluid tightly securedto the body cavity wall and extending transversely of the cavity, thediaphragm being centrally flexible to movably support the piston withinthe cavity. The indicator rod may be carried by the piston face remoteto the system fluid in the cavity for longitudinal axial movement intoand out of the cavity to variously project beyond the body. Indicatortravel guide means may be provided comprising structure slidablyengaging the cavity wall and adapted to move with the rod in guidingrelation.

The locking member herein may comprise an ele ment outside the cavityand extending transversely of the indicator rod longitudinal axis andhaving means cooperating with the indicator rod to selectively arrestrod movement dependent on direction of rod travel. In highly preferredembodiments, the locking member element has a ring portion encirclingthe indicator rod outward of the system fluid containing cavity, thering being sized to pass the rod when the ring is angularly disposednormal to the rod longitudinal axis and to engage the rod when the ringis deflected from a normal disposition. Means may be provided to deflectthe ring in response to movement of the rod toward the system fluidcontaining portion of the cavity including shoulder means adapted toengage the locking element in pivoting relation and deflect the ringportion of the element out of normal disposition relative to the rod,and a spring biasing the element into engagement with the shouldermeans. The locking member element may include a finger engageable tabprojecting from the ring portion thereof in engagement with the shoulderwhereby the element is pivoted about the shoulder, to a normaldisposition relative to the rod, the ring portion thereof being therebyreleasable from engagement with the rod. The rod itself may berectangular in crosssection to have sharply defined longitudinallyextended corners and flats therebetween, the rod corners being adaptedto engage the element ring portion in its deflected disposition.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be furtherdescribed as to an illustrative embodiment in conjunction with theattached drawing in which:

FIG. I is a medium longitudinal section of the device;

FIG. 2 is a view like FIG. 1, with the indicator rod undergoing pressuredisplacement;

FIG. 3 is a view in transverse section taken on line 33 in FIG. I; and

FIG. 4 is a fragmentary detail view of the rod arresting element inbinding engagement with the rod.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, inFIG. 1, the pressure indicator device 1 includes a body 2 formed ofthread connected first and second oppositely cup-shaped portions 3 and 4which define body cavity 5. The body eavity 5 openly communicates with afluid pressure system (not shown), to be monitored, through fitting 6projecting axialiy from first body portion 3, the fitting being adaptedto thread onto a nipple means (not shown) providing communication to thefluid pressure system. Base wall 7 of the body cavity is apertured at 8to admit pressurized fluid into the body cavity 5.

Within the cavity 5, a fluid pressure responsive indicator assembly 9 isprovided including a flexible diaphragm 10 perimetrically captured inannular body recess 11 in the body first portion 3 by ring 12 secured inthe recess by pin 13 and urged into the recess by shoulder 14 on thesecond body portion 4. Ring 12 has a coaxial annular projection 15 whichbears against the diaphragm 10 inward slightly of the actual diaphragmperimeter 16 to pinch the diaphragm at 17 against shoulder 17a as thefirst and second body portions are screwed together.

Diaphragm 10 is formed of rubber or other generally elastomeric, naturalor synthetic, material or other sheet material capable of rolling onitself without cracking or breaking. The diaphragm 10 extends across thediameter of body cavity 5 and is shaped to have a variable heigh annularroll 18 formed therein. Dual coil springs 19 are provided between thediaphragm 10 and seat member 21 to damp out resonance. The upper end 20of springs 19 engages seat member 21 between concentric inner and outerannular lips 22 and 23 respectively projects inwardly into the bodycavity 5 coaxially with the cavity longitudinal axis 24. The opposite,lower ends 25 of spring 19 is seated against the bottom 26 of movablecup 27. The cup 27 is carried by the flexible central portion ofdiaphragm 10 as a piston for movement within the body cavity 5. Cup 27has a wall portion 28 extending circularly about the spring 19 for adistance selected to normally limit travel of the cup and diaphragmwithin the body cavity to a predetermined range, by engagement with seatmember 21 circumferentially of the outer annular lip 23. The seat member21 is fixed in the second body portion 4 against shoulder 29. Aneccentric boss 30 forms shoulder means on the seat member 21, on theopposite side thereof from the annular lips 22, 23, for purposes to beexplained hereinbelow.

An indicator rod 31 is also included in the indicator assembly 9. Therod 31 may be rectangular in cross section and have graduated divisions32 on rod flats 33 (FIG. 3). The indicator rod 31 is reduced at 36 topass through opening 34 formed centrally of cup 27, and positionedcoaxial with the body cavity 5 by guide structure 38, an invertedtruncated cone apertured at 39 for system fluid passage into cavity 5secured to rod 31 by nut 40 threaded onto enlarged rod end 37 to bemovable with the cup carried by the diaphragm 10 as the semi-conicalguide structure slides along the cavity wall 5a. The indicator rod 31 issized to variously project axially through opening in the top (leftmost)wall of second body portion 4 in response to the location of the cup27in the body cavity 5.

The diaphragm 10 is fluid tightly perimetrically secured to the cavitywall at recess 11 and rod 31 is sealed therein at opening 34 so thatdiaphragm 10 rsponses to fluid pressure in lower cavity portion 42 bymovement upward (see FIG. 2) rolling on itself to vary the shape ofdiaphragm roll 18 and carrying the cup 27 and thus indicator rod 31upward also, against the force of concentric springs 19, therebyincreasing the projection 43 of the rod 3] beyond top wall a distancereadily measured by consulting Jhe graduations 32 on the rod flats 33.

Of course, if the fluid pressure were to drop in the lower cavityportion 42 the diaphragm 10 would normally tend to retreat under thereturn pressure of springs 19. If this were to happen, the maximumpressure in the fluid system during a certain period would not beascertainable after the fact, a condition which is unsatifactory inattempting to monitor in-flight conditions, after landing, in aircraftengine usage.

Accordingly, the invention provides means for arresting return movementof the rod 31 once advanced, but permitting further outward projectionthereof should a greater overpressure occur. Referring first to FIG. 3,a key 44 is provided which closely encircles indicator rod 31 aboutflats 33. The key is a flat metal member outside of and above cavity 5comprising a ring portion 45 and a tab 46 which projects laterally fromthe second body portion 4, a distance enabling easy finger manipulationthereof. A conical spring 47 is provided centered on rod 31 and betweenkey 44 and top wall 4a of the second body portion. In addition, key 44engages boss 30 which is located eccentrically within body portion 4 soas to pivot about the boss under the pressure of spring 47. In FIG. 2,the indicator assembly 9, comprising the center portion of diaphragm 10,cup 27 and rod 31 is advancing outwardly from the body under a greaterfluid pressure in lower cavity portion 42 and ring 45 engagement withthe rod, if any, tends to make the ring horizontal, or normal to the rodmovement direction along the body cavity and rod axis 24 whereby the rodis disengaged and movement is relatively easy.

In FIG. 1, the condition of the key 44 when the pressure is lowered isshown. There retromovement of the rod 31 permits key ring 45 to pivotabout boss 30 shoulder and become cocked relative to the rod. In thecooked condition of key 44 the horizontal opening 48 in key ring 45 istoo small for rod 31 passage and the ring binds the rod, preferably byengagement of the rod corners 49 with the ring opening 48. See FIGS. 3and 4. A subsequent increase in fluid pressure will free the rod 31 asany engagement tends to level the ring 45 and thus increase the throughopening 48 for the rod.

Thus, maximum pressure for any period is registered. The device 1 may berestored to its original zero setting (FIG. 1) by finger depression oftab 46 to horizontally orient the key 44 and ring portion 45 thereofrelative to rod 31, permitting springs 19 to return the rod to itsnonpressured, withdrawn position.

I claim:

1. Device for indicating highest fluid pressure experienced over time ina system experiencing varying pressure conditions, comprising a pressureresistant body defining a body cavity and having a rod passing in thetop wall portion of the device and communicating with said cavity and aboss on said top wall eccentric to said opening and port meanscommunicating said cavity continuously with system fluid pressure, apiston mounted and sealed within the body cavity between said openingand said port means for fluid pressure responsive movement, an indicatorrod carried by the piston for varying extension through said rod passingopening responsive to piston movement; and locking means limiting saidindicator rod travel to one way movement responsive to a higherexperienced pressure in the system comprising a locking member having aring portion encircling the indicator rod, said boss defining a pivotshoulder to operatively coact with the locking member so that the memberring portion binds the indicator rod against return movement if thepressure drops below the highest experienced pressure in the system.

2. Fluid pressure indicating device according to claim 1 including alsospring means resiliently biasing said member ring portion intoengagement with said boss.

3. Fluid pressure indicating device according to claim 1 including alsoa piston support, said piston support comprising a diaphragm fluidtightly secured to the body cavity wall and extending transversely ofthe cavity, said diaphragm being centrally flexible for movablysupporting the piston within said cavity.

4. Fluid pressure indicating device according to claim 3 in which saidindicator rod is carried by the piston face remote to said cavity portand for longitudinal axial movement into and out of said cavity tovariously project through said rod passing opening beyond the body.

5. Fluid pressure indicating device according to claim 4 including alsoindicator rod travel guide means comprising structure slidably engaging;the cavity wall and adapted to move with the rod in guiding relation.

6. Fluid pressure indicating device accordng to claim 1 in which saidrod is rectangular in cross section and has sharply definedlongitudinally extended corners and flats therebetween.

7. Fluid pressure device according to claim 7 including also a fingerengageable tab projecting from the ring portion of the locking memberfor pivoting said member about said boss to release the member ringportion from engagement with said rod.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,779,00 Dated December 18, 1973 Invent fl Charles Harry Smith It is certifiedthat error appears in the above-identified patent and that said LettersPatent are'hereby corrected as shown below:

Column 3 line 20; "variable heigh annular roll 18 formed therein. Dualcoil" should read -variable height annular roll 18 formed therein. Dualcoil--.

Column 3, line 60; "rsponses to fluid pressure in lower cavity portion42 by" should read responds to fluid pressure in lower cavity portion 42by-.

Column 3 line 66; "measured by consulting Jhe graduations 32 on the rod"should read --measured by consulting the graduations 32 on the rod-.

Column 4, line 52 "defining a body cavity and having a rod passing inthe" should read --defining a body cavity and having a rod passingopening in the-.

Column 6 line 7; "6 Fluid pressure indicating device accordng to claim"should read -6 Fluid pressure indicating device according to claim.

Column 6 line 11; "7 Fluid pressure device according toclaim 7 includ"should read -7 Fluid pressure device according to claim 6 includ- Signedand sealed this 13th day of August 1974.

(SEAL) Attest:

McCOY M. GIBSON, JR. C MARSHALL DANN Attesting Officer Commissioner ofPatents

1. Device for indicating highest fluid pressure experienced over time ina system experiencing varying pressure conditions, comprising a pressureresistant body defining a body cavity and having a rod passing in thetop wall portion of the device and communicating with said cavity and aboss on said top wall eccentric to said opening and port meanscommunicating said cavity continuously with system fluid pressure, apiston mounted and sealed within the body cavity between said openingand said port means for fluid pressure responsive movement, an indicatorrod carried by the piston for varying extension through said rod passingopening responsive to piston movement; and locking means limiting saidindicator rod travel to one way movement responsive to a higherexperienced pressure in the system comprising a locking member having aring portion encircling the indicator rod, said boss defining a pivotshoulder to operatively coact with the locking member so that the memberring portion binds the indicator rod against return movement if thepressure drops below the highest experienced pressure in the system. 2.Fluid pressure indicating device according to claim 1 including alsospring means resiliently biasing said member ring portion intoengagement with said boss.
 3. Fluid pressure indicating device accordingto claim 1 including also a piston support, said piston supportcomprising a diaphragm fluid tightly secured to the body cavity wall andextending transversely of the cavity, said diaphragm being centrallyflexible for movably supporting the piston within said cavity.
 4. Fluidpressure indicating device according to claim 3 in which said indicatorrod is carried by the piston face remote to said cavity port and forlongitudinal axial movement into and out of said cavity to variouslyproject through said rod passing opening beyond the body.
 5. Fluidpressure indicating device according to claim 4 including also indicatorrod travel guide means comprising structure slidably engaging the cavitywall and adapted to move with the rod in guiding relation.
 6. Fluidpressure indicating device accordng to claim 1 in which said rod isrectangular in cross section and has sharply defined longitudinallyextended corners and flats therebetween.
 7. Fluid pressure deviceaccording to claim 7 including also a finger engageable tab projectingfrom the ring portion of the locking member for pivoting said memberabout said boss to release the member ring portion from engagement withsaid rod.